SYNTHESIS OF NOVEL CARBOSILANE DENDRITIC MACROMOLECULES

A series of carbosilane dendritic macromolecules grown from four directions of a tetrahedral central core has been synthesized and characterized. In the synthesis tetravinylsilane is used as the central core molecule and dichloromethylsilane as the propagation unit. Two reactions are involved in the synthesis of each generation: hydrosilylation of vinylsilane with dichloromethylsilane and nucleophilic replacement of silicon chloride by vinylmagnesium bromide. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation are obtained. The H-1 and C-13 NMR spectra are consistent with the proposed structures. The molecular weights of the resulting carbosilane dendrimers have been determined by vapor pressure osmometry or light scattering. Their experimental values are in very good agreement with the theoretical values. The dilute solution properties of these dendrimers are different from linear polymers.